Apparatus, systems and methods for medical device expansion

ABSTRACT

A system and method for manufacturing a medical device. The system can include a thermal chamber and an expander at least partially positioned within the thermal chamber. The expander can be configured to uniformly expand a medical device as the medical device is advanced over the heated expander and heat set the expanded medical device while the medical device is positioned on the heated expander. The method can include forming a medical device from a tube having a first diameter; uniformly expanding the medical device from the first diameter to a second diameter at which the medical device can be left within a body vessel, the medical device being expanded from the first diameter to the second diameter while being continuously positioned on an expander; and heat setting the expanded medical device at the second diameter while the medical device is positioned on the expander.

BACKGROUND OF THE INVENTION

I. The Field of the Invention

The present invention generally relates to the field of medical devices.More specifically, the present invention relates to methods, systems,and devices for manufacturing a self-expanding medical device.

II. Related Technology

The use of intravascular devices to treat cardiovascular diseases iswell known in the field of medicine. The need for a greater variety ofdevices to address different types of circumstances has growntremendously as the techniques for using intravascular devices hasprogressed. One type of intravascular device is a stent or scaffold.Stents and scaffolds are generally cylindrically shaped intravasculardevices that are placed within an artery (or other vessel within thebody) to hold it open. The device can be used to reduce the likelihoodof restenosis or recurrence of the blocking of a blood vessel and can beplaced within an artery on a permanent basis, such as a stent, or atemporary basis, such as a scaffold. In some circumstances, a stent orscaffold can be used as the primary treatment device where it isexpanded to dilate a stenosis and left in place.

A variety of stent or scaffold designs have been developed. Examplesinclude coiled wires in a variety of patterns that are expanded afterbeing placed within a vessel on a balloon catheter, helically woundcoiled springs manufactured from expandable heat sensitive metals,stents or scaffolds shaped in zig-zag patterns, and self-expandingstents or scaffolds inserted in a compressed state for deployment in abody lumen.

Stents and scaffolds can have various features. For instance, a stent orscaffold can have a tubular shape formed from a plurality ofinterconnected struts and/or legs that can form a series ofinterconnected rings. In the expanded condition, the stent or scaffoldcan have a cylindrical shape to expand in an artery. One material formanufacturing self-expanding stents or scaffolds is nitinol, an alloy ofnickel and titanium.

The conventional approach to manufacture a self-expanding stent orscaffold is to begin by laser cutting the design of the stent orscaffold from a tube having a diameter that is approximately equal tothe desired diameter of the compressed (i.e., unexpanded) stent orscaffold. The tube is then deburred to clean any imperfections due tothe cutting. Once the tube has been deburred, the tube is then expandedto the desired diameter, which is the diameter the stent will maintainwhen left within a body vessel. The tube is then heat set at the desiredexpanded diameter to maintain the tube at that diameter.

Conventionally, expanding the stent or scaffold to the desired expandeddiameter requires an iterative process: The tube is positioned on amandrel having a diameter that is slightly larger than the diameter ofthe compressed tube, thereby expanding the tube. Heat is applied to thetube while the tube is on the mandrel to heat set the tube at the newdiameter. The tube and mandrel are allowed to cool to complete the heatsetting, and the tube is then removed from the mandrel. This process isthen repeated with a slightly larger mandrel to expand the tube further.This iterative process of expanding the tube a little at a time isrepeated until the desired expanded diameter is attained.

Although the conventional manufacturing approach discussed abovegenerally yields acceptable self expanding medical devices, the approachhas some shortcomings. For example, it is cumbersome and time consumingdue, in large part, to the iterative heating and cooling processes. Inaddition, a significant amount of energy is used by heating andreheating the medical device and the mandrel during each iteration.Another shortcoming is that, in many instances, cracks are induced inthe stent or scaffold during conventional manufacturing due to undesiredtorque, tension, expansion, and/or compression.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention relate to the expansion of medical devicesincluding implantable medical devices such as stents or scaffolds.

In one embodiment, a method of manufacturing a medical device caninclude forming a medical device from a tube having a first diameter;uniformly expanding the medical device from the first diameter to asecond diameter at which the medical device can be left within a bodyvessel, the medical device being expanded from the first diameter to thesecond diameter while being continuously positioned on an expander; andheat setting the expanded medical device at the second diameter whilethe medical device is positioned on the expander.

In another embodiment, a method of manufacturing a medical device caninclude positioning a medical device on a transport assembly having aplurality of transport mechanisms, the transport mechanisms beingarranged generally parallel to a central longitudinal axis; positioninga portion of the transport assembly on an expander so that the medicaldevice becomes positioned radially over the expander; radially expandingthe medical device with the expander while the medical device ispositioned on the transport assembly; and heat setting the expandedmedical device while the medical device is positioned on the expander,the acts of radially expanding the medical device and heat setting theexpanded medical device being performed while the medical device ispositioned in a heated thermal chamber.

In another embodiment, a system for uniformly expanding and heat settinga medical device can include a thermal chamber and an expander at leastpartially positioned within the thermal chamber. The thermal chambermaintains the expander at a predetermined elevated temperature. Theexpander is configured to uniformly expand a medical device as themedical device is advanced over the heated expander and heat set theexpanded medical device while the medical device is positioned on theheated expander.

In some embodiments of the invention, the medical device can be placedover a transport assembly having a plurality of transport mechanisms.The transport mechanisms can then be expanded with an expander, therebyuniformly expanding the medical device. The medical device can beexpanded at any operable temperature. In some embodiments, the medicaldevice can be expanded while within a temperature controlled zone. Insome embodiments, the medical device can be heat set while in theexpanded state.

The transport mechanisms may engage with corresponding transport guides,such as recesses, grooves, or channels, in the expander that keep thetransport mechanisms uniformly spaced circumferentially around theexpander, while the transport mechanisms provide a separation betweenthe medical device and the expander body. As a result, the transportmechanisms can act as a transport to reduce friction that may otherwiseoccur between the medical device and the expander during expansion ormanufacture of the medical device. By reducing friction, the medicaldevice can be expanded with less susceptibility to adverse effects suchas compression, tension, fracturing, torquing, bending, unevenexpansion, and the like or any combination thereof.

A medical device can thus be expanded in one embodiment by positioningthe medical device over a transport assembly that includes a pluralityof transport mechanisms, such as wires. The transport mechanisms can bearranged generally parallel to a central longitudinal axis of theexpander. Next, at least a portion of the transport assembly and atleast a portion of the medical device can be positioned over anexpander, such as a mandrel. Then, at least a portion of the medicaldevice can be radially expanded with the expander.

The expander may have a central longitudinal axis and a body having anouter surface. The outer surface may have a plurality of longitudinaltransport guides, such as wire recesses, grooves, or channels definedtherein. The longitudinal transport mechanisms can be configured to bepositioned at least partially within the transport guides to guide thetransport assembly for translation of the transport assembly withrespect to the expander, parallel to the longitudinal axis. The expandermay also have a portion with a first diameter, a portion with a secondlarger diameter, and a transition portion that transitions the expanderfrom the first diameter to the second diameter.

In one embodiment, the medical device can be expanded by axiallytranslating the expander relative to the medical device. The transportmechanisms can transport the medical device by reducing friction betweenthe medical device and the expander as the expander moves axially (orwhile the medical device moves axially along the expander). Duringheat-setting of the medical device, the medical device can be heat-setin the expanded position, for instance.

In one embodiment, the transport assembly can comprise a wire array andthe transport mechanisms can comprise the wires that make up the wirearray. Correspondingly, the transport guides can comprise wire guidesarranged generally parallel to the central longitudinal axis of theexpander so as to receive and guide the wires over the expander. Themedical device can be expanded by positioning the medical device overthe wires of the wire array and then moving the wire array toward theexpander so that the wires are received within the wire guides of theexpander. Next, at least a portion of the wire array and at least aportion of the medical device can be advanced onto the expander. Themedical device can then be radially expanded by the expander as themedical device moves with the wires within the wire guides.

These and other advantages and features of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. In the drawings,like numerals designate like elements. Furthermore, multiple instancesof an element may each include separate letters appended to the elementnumber. For example two instances of a particular element “20” may belabeled as “20a” and “20b”. In that case, the element label may be usedwithout an appended letter (e.g., “20”) to generally refer to everyinstance of the element; while the element label will include anappended letter (e.g., “20a”) to refer to a specific instance of theelement.

FIG. 1 illustrates an exploded view of a system for expanding a medicaldevice according to one embodiment;

FIG. 2 is a perspective view of the expander shown in FIG. 1;

FIGS. 3A, 3B, and 3C are cross sectional views of the expander of FIG.2, taken along section lines 3A-3A, 3B-3B, and 3C-3C, respectively, ofFIG. 2;

FIGS. 4A-4C illustrate a method for expanding a medical device using thesystem shown in FIG. 1, according to one embodiment;

FIGS. 5A-5C illustrate a method for deploying a medical device accordingto one embodiment;

FIGS. 6A-6B is a side view of an expander according to anotherembodiment;

FIGS. 7A-7B are cross sectional views of an expander according toanother embodiment:

FIGS. 8A-8C illustrate a method for expanding a medical device using thesystem shown in FIG. 1, according to another embodiment;

FIG. 9 illustrates an exploded view of a system for expanding a medicaldevice according to another embodiment;

FIG. 10 is a end view of the integrated wiring guide shown in FIG. 9;

FIGS. 11A-11B illustrate a method for expanding a medical device usingthe system shown in FIG. 9, according to one embodiment; and

FIGS. 12A-12B illustrate embodiments for rotationally aligning anintegrated wiring guide and an expander.

DETAILED DESCRIPTION

As used in the specification and appended claims, directional terms,such as “top,” “bottom,” “up,” “down,” “upper,” “lower,” “proximal,”“distal,” and the like are used herein solely to indicate relativedirections and are not otherwise intended to limit the scope of theinvention or claims.

Methods and devices are provided herein for expanding a medical device.The methods provided through the systems and devices are repeatable andreduce the possibility of incorrectly expanding medical devices duringthe manufacturing process. Further, the methods provided herein reducethe possibility of undesired torque, tension, expansion and compressionof the stent or scaffold during manufacture.

In at least one embodiment, a method for expanding a medical deviceincludes placing the medical device over longitudinally orientedtransport mechanisms, such as wires. The medical device is then expandedwhile in place over the transport mechanisms. The transport mechanismscan provide a bearing-type surface to allow for even expansion whilereducing the potential for deformation. In at least one embodiment, thetransport mechanisms can be positioned on an expander with transportguides, such as recesses, grooves, or channels, for maintaining adesired spacing between the transport mechanisms. In at least oneembodiment, the expander can cause the medical device to expand withoutthe expander itself expanding. In other embodiments, the expander can beexpanded with a separate expanding mechanism that is inserted into theexpander to expand the expander, and thereby expand the transportmechanisms and the medical device. Accordingly, a variety of methods,systems, and devices can be used to expand a medical device overlongitudinally oriented transport mechanisms, as will be discussed inmore detail below.

Reference will now be made to figures wherein like structures will beprovided with like reference designations. It is understood that thedrawings are diagrammatic and schematic representations of exemplaryembodiments of the invention, and are not limiting of the presentinvention nor are they necessarily drawn to scale.

FIG. 1 illustrates one embodiment of a system 100 for expanding amedical device 110, such as a vascular device, extending between aproximal end 112 and a spaced apart distal end 114. For ease ofreference, a coordinate system will be referenced in discussing system100 (and the other systems discussed herein) that includes a centralaxis C. Elements that are generally parallel to central axis C will alsobe described as being longitudinally oriented relative to central axis Cwhile elements that are generally transverse or perpendicular to centralaxis C will be described as being radially oriented relative to centralaxis C. In addition, the direction indicated by arrow 102 that isparallel to central axis C will be referred to as the “proximal”direction and the opposite direction will be referred to as the “distal”direction. As such, movement in the proximal and distal directions maybe referred to as proximal and distal movement, respectively.

In the illustrated embodiment, system 100 includes a longitudinallyoriented transport assembly in the form of a wire array 120 having aplurality of individual transport mechanisms in the form of wires 125extending from a proximal end 126 to a distal end 128. The number ofwires can vary, as discussed below. The wires can be made of metals oralloys, such as, but not limited to, stainless steel, titanium,tantalum, tungsten, or alloys thereof, nickle chromium (commonly knownas nichrome) quartz, glass, glass thread, polymers, or other hightemperature material. Using wires that can sustain high temperaturesallows the medical device to be heat treated (e.g., such as shape setusing heat).

Although reference has been made to the use of wires and a wire array,respectively, as the transport mechanisms and transport assembly, oneskilled in the art will appreciate that other structures can alsoperform the functions of the transport mechanisms and transportassembly. For example, and not by way of limitation, other structuresthat can be used as the transport mechanisms include strips, ribbons,yarns, threads, rods, or other structures having the desired strengthand rigidity, with associated flexibility and resiliency to allow thestructure to i) provide a bearing-type surface for the medical device,ii) separate at least a portion of the medical device from an expanderor expander mechanism during a manufacturing process, or iii) otherwiseperform other functions described or identified from the descriptioncontained herein.

Wire array 120 is configured to receive medical device 110 thereon.System 100 also includes an expander 130, which can also be described asa mandrel in the present embodiment. Expander 130 includes features thatare configured to guide and/or partially receive wire array 120.

For example, expander 130 illustrated in FIG. 2 generally includes abody 200 having an outer surface 202 extending between a proximal endface 204 on a proximal end 200A and a distal end 200B. Body 200 can havea first diameter D_(A) at proximal end 200A that transitions to a seconddiameter D_(B) that is greater than the first diameter D_(A). In atleast one embodiment, the second diameter D_(B) is at distal end 200B,though it will be appreciated that the first diameter D_(A) cantransition to any number of varying diameters at any number of locationsbetween proximal end 200A and distal end 200B.

In at least one embodiment, proximal end 200A and distal end 200B caneach be as long or longer than medical device 110 (FIG. 1) which system100 (FIG. 1) is configured to expand. Such a configuration can providesupport for medical device 110 both before and after medical device 110is expanded as the diameter of the portion of body 200 is increased. Asthe diameter of body 200 increases, body 200 continues to support wirearray 120 which, in turn, supports and provides a bearing-type surfacefor medical device 110 (FIG. 1).

In the illustrated embodiment, body 200 transitions from the firstdiameter D_(A) to the second diameter D_(B) at a transition portion200C. The depicted transition portion 200C includes a ramped profilewith a shoulder portion 205A associated with proximal end 200A and ashoulder portion 205B associated with distal end 200B. As such,transition portion 200C is substantially frustoconically shaped in thedepicted embodiment. It will be appreciated, however, that other shapesare possible and that transition portion 200C and shoulder portions205A, 205B can have any profile, and that any number of transitionportions can be provided.

In the depicted embodiment, the diameters of proximal and distal ends200A and 200B remain substantially unchanged along the lengths of therespective end. That is, the diameter D_(A) of proximal end 200A remainssubstantially unchanged along the entire length of proximal end 200A andthe diameter D_(B) of distal end 200B remains substantially unchangedalong the entire length of distal end 200B. However, if desired thediameter of proximal end 200A and/or the diameter of distal end 200B caninstead vary along the length of the corresponding end. For example, inone embodiment, the diameter D_(B) of distal end 200B progressivelyincreases as distal end 200B extends distally away from transitionportion 200C. In that embodiment, distal end 200B can have a rampedprofile similar to transition portion 200C. That embodiment can be usedto expand and heat set medical devices into a tapered heat setconfiguration, such as, e.g., a tapered stent.

To correspond to wires 125, transport guides in the form of wire guides210 are defined on outer surface 202 of body 200 and are distributedcircumferentially about outer surface 202. Each wire guide 210 extendslongitudinally between end face 204 at proximal end 200A, throughtransition portion 200C, and toward distal end 200B. Wire guides 210 areconfigured to receive wires 125 of wire array 120 (FIG. 1). Such aconfiguration can constrain wires 125 and keep them in a particularspatial orientation during expansion of medical device 110. As such, thenumber of wire guides 210 should be equal to or greater than the numberof wires 125 in wire array 120. Ideally, the number of wire guides 210equals the number of wires 125.

Further, wire guides 210 can control friction between medical device 110and body 200 of the expander 130 during expansion. For instance,changing the depth of wire guides 210 changes the height of wires 125extending above surface 202 of body 200 to function and provide abearing-type surface upon which at least a portion of medical device 110(FIG. 1) rests. With more of each wire 125 exposed above surface 202,there is a decreased likelihood that a portion of medical device 110(FIG. 1) frictionally engages body 200 upon axial movement of medicaldevice 110 (FIG. 1) relative to body 200, or vice versa.

This limits the possibility of unwanted frictional contact that coulddamage medical device 110 (FIG. 1) due to the application of undesiredtorque, tension, expansion, and/or compression to medical device 110(FIG. 1) during the manufacturing processes. In one configuration,therefore, wires 125 extend radially outward from wire guides 210sufficiently to prevent contact between medical device 110 (FIG. 1) andthe body 200. In another configuration, wires 125 extend radiallyoutward from wire guides 210 sufficiently to prevent contact that wouldbe sufficient to damage medical device 110 (FIG. 1).

Transition portion 200C may have a tapered configuration with a slopethat allows expansion of medical device 110 to proceed smoothly withoutunduly expanding a portion of medical device 110 relative to an adjacentportion of the medical device. Further, the cross sectional shape ofexpander member 130 is typically similar in all portions and thus theexpansion of medical device 110 can be to the same shape. For example,as shown in FIGS. 3A-3C, the cross sectional shape of expander 130 inthe depicted embodiment is generally circular for each portion.

In alternative embodiments, the portions of expander 130 may havedifferent cross sectional shapes. This may allow, for example, a medicaldevice to be expanded from a circular cross section to some othercross-sectional shape, such as, but not limited to, an oval crosssection, a polygonal cross section, or some other regular or irregulargeometric cross section. In addition, the expander 130 can be shaped toaccommodate the shape of an anticipated deployment site. As a result,the final cross sectional area of the medical device can vary. Also, thecross sectional shape can vary as well.

Expander 130 can be fabricated from a variety of different materials.For instance, expander 130 can be made from metals, alloys, plastics,polymers, composites, ceramics, or any combinations thereof. Expander130 can alternatively be made of other materials, as desired, based uponthe particular medical device being formed and the temperatures and/orpressures that expander 130 is to withstand during the manufacture ofthe medical device. In another configuration, expander 130 can be platedwith another material, such as, but not limited to, a chromium coatingor a diamond chromium coating, such as Armoloy®, or a nickel-phosphoralloy, such as NEDOX® 10K™-1 or MAGNAPLATE HMF, both manufactured byGeneral Magnaplate Corporation. In one embodiment, expander 130 can befabricated from stainless steel or a nickel titanium alloy, such asnitinol. In various embodiments, the materials forming expander 130 canwithstand a temperature from about 250° C. to about 600° C., from about250° C. to about 650° C., from about 300° C. to about 600° C., fromabout 300° C. to about 550° C., from about 450° C. to about 600° C.,from about 450° C. to about 550° C., or some other range known to oneskilled in the art in view of the teachings contained herein.

FIG. 3A illustrates a cross-sectional view of proximal end 200A ofexpander 130 taken along section line 3A-3A of FIG. 2, FIG. 3Billustrates a cross-sectional view of distal end 200B taken alongsection line 3B-3B, and FIG. 3C illustrates a cross-sectional view oftransition portion 200C taken along section line 3C-3C of FIG. 2.

As shown particularly in FIG. 3A, proximal end 200A has a generallycircular or tubular cross sectional profile with the first diameterD_(A). A guide opening or lumen 320 can longitudinally extend intoexpander 130 from proximal end face 204, if desired, and extend at leastpartially through expander 130, as shown in FIGS. 3A-3C, although thisis not required. In at least one embodiment, guide opening 320 iscentered on central axis C of the body. Guide opening 320 can be used toguide wire array 120 and medical device 110 onto the expander 130, asdiscussed below.

Wire guides 210 are positioned circumferentially about outer surface 202of body 200 (FIG. 2) and about proximal end 200A. In at least oneembodiment, each wire guide 210 can include a profile that is partiallycircular, although various other profiles are possible which receivewire 125.

Wire guides 210 are separated by angular separations 310 relative tocentral axis C. In the depicted embodiment, the angular separationsbetween the individual wire guides are substantially equal, but this isnot required. In other embodiments, the angular separations can bedifferent and wire guides 210 can be arranged in a manner that ispartially symmetrical or asymmetrical.

Each wire guide 210 can have any desired depth and dimension and shape.In at least one embodiment, each wire guide 210 can include a recess,groove, or channel having a generally hemispherical inner portion. Inother embodiments, the recess, groove, or channel can be square shaped,angular, and the like. Further, each recess, groove, or channel can havean inner portion having a central angle of any size. Finally, thearrangement of the wire guides provides, in one embodiment, aspline-type geometry to keep the wires uniformly spacedcircumferentially around the expansion member. For instance, adjacentlypositioned wire guides 210 can be separated by a portion of body 200 ora spline 212 as illustrated in FIG. 3A.

For ease of reference, positions of wire guides 210 relative to otherelements will be described with reference to the central portion of therecesses defining wire guides 210. It will be appreciated that otherreference points can be used to describe relative positions. In at leastone embodiment, wire guides 210 are positioned about the perimeter ofproximal end 200A such that angular separations 310 are substantiallyequal.

As illustrated in FIG. 3B, distal end 200B of body 200 (FIG. 2) also hasa generally circular or tubular cross sectional profile, but with thesecond diameter D_(B). As previously discussed, the second diameterD_(B) is greater than the first diameter D_(A). Further, at or neardistal end 200B, wire guides 210 can be separated by angular separations312. In at least one embodiment, angular separations 312 can besubstantially equal with respect to distal end 200B. Further, in atleast one embodiment angular separations 312 can be substantially equalto angular separations 310 between wire guides 210 on proximal end 200A(FIG. 3A). Accordingly, angular separations 312 can remain substantiallyconstant while the diameter of body 200 (FIG. 2) increases.

The diameter of body 200 increases from the first diameter D_(A) to thesecond diameter D_(B) through transition portion 200C. As illustrated inFIG. 3C, transition portion 200C provides an angular separation 314 thatis substantially similar to angular separations 310, 312 respectivelyassociated with proximal end 200A (FIG. 3A) and distal end 200B (FIG.3B) while increasing the diameter of body 200 (FIG. 2). Such aconfiguration can allow wire guides 210 to maintain wires 125 (FIG. 1)of wire array 120 (FIG. 1) evenly distributed, which can evenlydistribute forces exerted by the wires during an expansion process.

Although the above-described embodiment includes evenly distributed wireguides 210, one skilled in the art will appreciate that in otherconfigurations wire guides 210 may be unevenly distributed along all ora portion of the length of body 200. For instance, in anotherembodiment, the angle of angular separation 310 of wire guides 210 at atleast a portion of proximal end 200A can be smaller than the angle ofangular separation 312 at at least a portion of distal end 200B.Similarly, in another embodiment, the angle of angular separation 310 ofwire guides 210 at at least a portion of proximal end 200A can begreater than the angle of angular separation 312 at at least a portionof distal end 200B. It will be understood that various othercombinations of angular separations are also possible and known to thoseskilled in the art in view of the teaching contained herein.

Various methods of operation will be discussed below. It will beappreciated that when discussing movement of elements with respect toeach other, either element can move while the other is stationary, orboth elements can move. For example, if element A is said to movedistally toward element B, this means that i) element A can move in thedistal direction while element B remains stationary, ii) element B canmove in the proximal direction while element A remains stationary, oriii) both elements can move toward each other.

FIGS. 4A-4C illustrate one embodiment of a method of uniformly expandingmedical device 110 using an axial guide 400 to move wire array 120 withrespect to expander 130. Axial guide 400 extends between a proximal end402 and a distal end 404 and is sized to be insertable into guideopening 320 in expander 130. As such, axial guide 400 can have asubstantially uniform cross sectional shape along its length, ifdesired.

As with the other method embodiments described herein, while anexemplary order of steps will be described in expanding the medicaldevice, it will be appreciated that the steps may be performed indifferent orders, that additional steps may be included, and/or thatsteps may be omitted.

Before expanding a medical device, the medical device must first beinitially cut out or otherwise formed. For example, the medical devicecan be laser cut from a tube having a diameter that is approximatelyequal to the desired diameter of the compressed (i.e., unexpanded)medical device. The tube can then be deburred to clean any imperfectionsdue to the cutting. Other initial forming methods may also be used.

As shown in FIG. 4A, the expansion process can begin by positioning wirearray 120 over axial guide 400. Thereafter, medical device 110, such as,e.g., a stent or scaffold as shown in the depicted embodiment, can bepositioned over wire array 120, and, consequently, over axial guide 400.In one embodiment, proximal end 126 of wire array 120 is attached orotherwise coupled to axial guide 400. In another embodiment, axial guide400 includes a stop portion (not shown) that extends radially outward sothat the proximal end 126 of wire array 120 butts up against the stopportion, thereby causing wire array 120 to move axially as axial guide400 moves. In another embodiment, wire array 120 is not attached toaxial guide 400 and is moved independent of axial guide 400.

Once wire array 120 and medical device 110 are in position over axialguide 400 as shown in FIG. 4A, medical device 110 can then be positionedover proximal end 200A of expander 130. To do this, expander 130 can bepositioned on axial guide 400 by way of guide opening 320. That is,axial guide 400 can be received into guide opening 320 of expander 130at proximal end face 204 so that wire array 120 and medical device 110can be advanced along axial guide 400 in the distal direction, denotedby arrow 406, toward expander 130. In one embodiment, wire array 120 andmedical device 110 are moved distally by distal movement of axial guide400. In another embodiment, a separate pushing mechanism can be used toadvance medical device 110 and/or wire array 120 distally (see, e.g.,advancement mechanism 932 in FIG. 9).

As wire array 120 and medical device 110 are distally advanced, distalend 128 of wire array 120 arrives at proximal end face 204 of proximalend 200A of expander 130. Thereafter, distal ends 128 of at least someof wires 125 can be positioned on wire guides 210 formed on proximal end200A of expander 130. Wire array 120 and medical device 110 can then beadvanced further distally so that wires 125 slide distally along wireguides 210.

As shown in FIG. 4A, medical device 110 can be positioned within athermal chamber 410, such as an oven, a refrigerator, or any otherdevice or apparatus configured to regulate thermal chamber 410 at one ormore desired temperatures. The desired temperature(s) is/are whatevertemperature(s) facilitate expansion and heat setting of the medicaldevice. This can be affected by the material of the medical device amongother factors. Thermal chamber 410 can be configured to maintain medicaldevice 102 at a same predetermined temperature throughout preheating,expansion, and heat setting of medical device 102 or to heat medicaldevice 102 to different predetermined temperatures for two or three ofthe steps. In one embodiment, the thermal chamber can be configured toheat medical device 110 to between about 450° C. to about 600° C. Ofcourse, other temperature ranges can also be used.

Thermal chamber 410 can have an axial length that is substantially equalto or slightly longer than medical device 110. As such, thermal chamber410 can remain axially aligned with respect to medical device 110 (i.e.,thermal chamber 410 can move proximally or distally with medical device110) so that the medical device remains positioned within thermalchamber 410 as medical device 110 and expander 130 are moved withrespect to each other. For ease of reference, thermal chamber 410 willbe described herein as a heating device that heats medical device 110and expander 130 and is illustrated schematically and in cross-section.

In at least one embodiment, axial guide 400 can be supported by supports420 that maintain axial guide 400 and/or wire array 120 radially alignedrelative to thermal chamber 410. Supports 420 can allow axial guide 400to move proximally and distally along central axis C, thereby allowingthe elements that axial guide 400 is supporting to be moved into desiredpositions within thermal chamber 410.

Supports 420 can allow axial guide 400 to proximally and distally movemedical device 110, wire array 120, and/or expander 130 into and out ofthermal chamber 410. If required, supports 420 can be moved radiallyaway from axial guide and/or wire array 120 during axial movement ofwire array 120 and/or medical device 110 to allow wire array 120 and/ormedical device 110 to pass.

Once wire array 120 and medical device 110 are positioned in thermalchamber 410, medical device 110 can be preheated by thermal chamber 410to a desired temperature.

Once medical device 110 is preheated to the desired temperature, thedistal advancement of wire array 120 and medical device 110 can continueuntil medical device 110 becomes positioned on proximal end 200A ofexpander 130, as illustrated in FIG. 4B. The shape and configuration ofwire guides 210 help retain wires 125 in position relative to expander130. This configuration can allow wire guides 210 to guide wires 125 aswires 125 move distally over expander 130.

As shown in FIG. 4B, thermal chamber 410 can move distally with medicaldevice 110 so that thermal chamber 410 remains longitudinally alignedwith medical device 110 and can continue heating medical device 110.

With medical device 110 preheated to the desired temperature, wire array120 and medical device 110 can be advanced further distally by axialguide 400. As shown in FIG. 4C, as wire array 120 and medical device 110advance distally, increasingly larger diameters of transition portion200C of expander 130 urge wires 125, which are positioned within wireguides 210, radially outward. As wires 125 are urged radially outward,wires 125, in turn, urge medical device 110 uniformly radially outwardbeginning with distal end 114 of medical device 110.

Wires 125 act as a bearing-type surface that supports and guides medicaldevice 110 while maintaining a separation between medical device 110 andexpander 130. In this manner, wires 125 help reduce frictionalengagement between medical device 110 and expander 130. As a result, thelikelihood is reduced of medical device damage from excessive stressesassociated with induced torque, tension, compression and/or expansion ofthe medical device during manufacture

As medical device 110 passes distally through transition portion 200C ofexpander 130, distal end 114 of medical device 110 becomes supported ondistal end 200B of expander 130. As medical device 110 continues to movedistally, proximal end 112 of medical device 110 is also uniformlyexpanded by the cooperation of transition portion 200C, expander 130,and wires 125 until proximal end 112 also becomes supported on distalend 200B of expander 130, as shown in FIG. 4C.

At this point, medical device 110 is fully expanded to the seconddiameter D_(B) (FIG. 3B) and is supported at that diameter on distal end200B of expander 130. In the expanded configuration, medical device 110generally takes on the shape of distal end 200B. For example, in thedepicted embodiment, distal end 200B is substantially cylindrical,thereby causing medical device 110 to also have a substantiallycylindrical shape in the expanded configuration. Alternatively, if atapered medical device is desired, an expander can be used in which thediameter D_(B) of distal end 200B progressively increases as distal end200B extends distally away from transition portion 200C, as discussedabove. Because of the changing shape of distal end 200B, medical device110 is caused to have a tapered shape in the expanded configuration.Other expanded medical device shapes can also be obtained by usingexpanders having distal ends with corresponding shapes.

As shown in FIG. 4C, thermal chamber 410 can continue to move distallywith medical device 110 so that thermal chamber 410 remainslongitudinally aligned with medical device 110 when medical device 110is expanded and can continue heating medical device 110. As discussedabove, during expansion of medical device 110, thermal chamber 410 canmaintain medical device 110 at the same predetermined temperature asduring preheating, or can cause medical device to be heated to adifferent predetermined temperature.

Medical device 110 can remain within thermal chamber 410 after theexpansion process, if desired. To do so, thermal chamber 410 can remainaxially aligned with medical device 110 when medical device 110 is inthe expanded configuration, as shown in FIG. 4C. In one embodiment, theexpanded medical device 110 can remain within thermal chamber 410 for apredetermined period of time to heat set medical device 110 in theexpanded configuration. As discussed above, during heat setting ofmedical device 110, thermal chamber 410 can maintain medical device 110at the same predetermined temperature as during preheating and/orexpansion or can cause medical device to be heated to a differentpredetermined heat setting temperature.

In at least one embodiment, while in position on expander 130, wires 125may extend only slightly above outer surface 202 of body 200. Such aconfiguration may cause medical device 110 to contact outer surface 202of expander 130 as well as wires 125 during the expansion process.Alternatively, wires 125 may extend sufficiently above outer surface 202of body 200 so that only wires 125 contact medical device 110 duringexpansion while wires 125 are held in place by wire guides 210.

By substantially limiting contact of medical device 110 to only wires125, frictional forces can be reduced compared to those generatedthrough contact between medical device 110 and expander 130. Thisreduces the likelihood that medical device 110 will frictionally bindwith expander 130 during heat setting or become damaged due to excessivetorque, tension, expansion, and/or compression.

Further, the interaction between wires 125 and expansion member 130 canhelp ensure that expander 130 tracks a path that is generally parallelto central axis C as expander 130 expands medical device 110. Tracking agenerally parallel path can in turn help provide even stressdistribution of the stresses induced by the interaction of medicaldevice 110 and expander 130. This even stress distribution also reducesthe likelihood of medical device damage due to excessive torque,tension, expansion, and/or compression.

Once the heating and expansion process is complete, medical device 110can be removed from heating chamber 410 and expander 130 and wire array120. In one embodiment, medical device 110 can be removed from heatingchamber 410 by essentially reversing the process discussed above. Thatis, axial guide 400 can be axially moved in the opposite direction(i.e., proximally), thereby moving wire array 120 and medical device 110away from expander 130 until wire array 120 and medical device 110 areseparated from expander 130. In one embodiment, the distal end 128 ofwire array 120 can remain engaged with expander 130 after the expandedmedical device 110 has become separated from expander 130.

As discussed above, in at least one embodiment, medical device 110 canbe expanded and heat set using the method discussed above. In thisembodiment, because of the heating and expansion process, the medicaldevice is unconstrained in the expanded position. The medical device canthen be constrained prior to deployment.

FIGS. 8A-8C illustrate another embodiment of a method of uniformlyexpanding (and heat setting, if desired) medical device 110 using a wirearray. The method illustrated in FIGS. 8A-8C is similar to the methoddiscussed above with respect to FIGS. 4A-4C. However, in the alternativemethod, a thermal chamber 800 is used having a different configurationthan thermal chamber 410. Specifically, instead of having an axiallength substantially equal to or slightly longer than medical device110, thermal chamber 800 has an axial length that is substantially thesame as or slightly longer or shorter than expander 130, as shown inFIGS. 8B and 8C.

As a result, thermal chamber 800 can remain axially aligned with respectto expander 130 (i.e., thermal chamber 800 can remain fixed withexpander 130 or move proximally or distally with expander 130) insteadof axially moving with medical device 110. This allows expander 130 andmedical device 110 to both remain positioned within thermal chamber 800when medical device 110 is mounted on expander 130, even as medicaldevice 110 advances on expander 130.

In a similar manner to the method discussed above, the process can beginby positioning wire array 120 over axial guide 400, then positioningmedical device 110 over wire array 120 and advancing axial guide 400distally toward expander 130, as shown in FIG. 8A. In a similar mannerto the method discussed above, wire array 120 and medical device 110 canbe advanced distally on expander 130 to pre-heat and then expand andheat-set medical device 110, as shown in FIGS. 8B and 8C. Similar to themethod discussed above, medical device 110 can remain within thermalchamber 800 during the expansion process and for a predetermined periodof time thereafter, if desired, to heat set the expanded medical device.To do this, however, thermal chamber 800 does not need to move withmedical device 110, but can remain axially aligned with expander 130 byremaining stationary as medical device 110 moves distally.

Whether one uses the shorter thermal chamber 410 or the longer thermalchamber 800 is generally a matter of design choice. In some aspects,longer thermal chamber 800 may provide some benefits over shorterthermal chamber 410. For example, when using thermal chamber 800,expander 130 can be maintained within thermal chamber 800 during theentire expansion process. As a result, once expander 130 is heated to adesired temperature by thermal chamber 800, the temperature of expander130 can be maintained at a substantially constant value, such as apredetermined heat setting value of medical device 110, even betweenuses. Because of this, no time is lost waiting for expander 130 tosubsequently heat up each time a different medical device 110 is to beexpanded and heat set.

In contrast, when using shorter thermal chamber 410, different portionsof expander 130 may cool and require a finite amount of time to becomere-heated each time a medical device needs to be expanded and heat setdue to the axial movement of thermal chamber 410 with medical device110. This can result in delays when expanding and heat setting multiplemedical devices. However, thermal chamber 410 may require less energythan thermal chamber 810 due to the shorter length. It is appreciatedthat other lengths can also be used for the thermal chamber, if desired.

FIG. 9 illustrates another embodiment of a system 900 for uniformlyexpanding (and heat setting, if desired) medical device 110. Similar tosystem 100, system 900 includes a wire array 902 having a plurality ofwires 904 configured to be advanced onto an expander 906. However,instead of using a separate axial guide to advance the wires, system 900combines wire array 902 and an axial guide 916 along with an advancementguide 908, to form an integrated advancement guide assembly 910. System900 also includes an advancement mechanism 932 to aid in advancingmedical device 110 over advancement guide assembly 910 and onto expander906.

As shown in FIGS. 9 and 10, advancement guide 908 comprises a rod or thelike that extends distally to a distal facing end face 920. Similar toaxial guide 400, axial guide 916 is sized to be insertable into a guideopening within expander 906. Axial guide 916 extends distally from endface 920 of advancement guide 908 and has a smaller cross sectional areathan advancement guide 908, as particularly shown in FIG. 10. Also asshown in FIG. 10, axial guide 916 generally extends from the center ofend face 920, although this is not required. Axial guide 916 can beintegrally formed with advancement guide 908 or rigidly attachedthereto, such as by welding, adhesive, or any other attaching methodknown in the art. In some embodiments, axial guide 916 can be omitted,if desired.

As shown in FIG. 9, wire array 902 extends between a proximal end 922,positioned at end face 920, and a distal end 924. At proximal end 922,each wire 904 is welded or otherwise attached to advancement guide 908at end face 920 to form advancement guide assembly 910. Alternatively,each wire 904 can be integrally formed with advancement guide 908 at endface 920. The number of wires in wire array 902 can vary. Althoughsixteen wires 904 are shown in FIG. 10, other numbers of wires canalternatively be used. For example, eight, ten, twelve, or any othernumber of wires can be used. However, for each wire, a correspondingwire guide should be found in the expander to receive the wire.

As shown in FIG. 10, wires 904 of wire array 902 can be positionedradially about end face 920 so that the radially outer-most edge of eachwire 904 is axially aligned with the outer surface of advancement guide908 at end face 920. That is, the diameter of wire array 902, taken atthe radially outermost portion of wires 904 can be substantially equalto the diameter of advancement guide 908. By doing so, a smoothtransition can be formed between advancement guide 908 and wire array902, allowing easy passage between the two for medical device 110. Wires904 can also be configured to radially encircle axial guide 916, ifaxial guide 916 is used. As such, wires 904 can longitudinally alignwith wire guides 210 positioned on expander 906.

In the embodiment depicted in FIGS. 9 and 10, axial guide 916 islongitudinally longer than wire array 902 and thus extends beyond distalend 924 of wire array 902. In other embodiments, wire array 902 islonger than axial guide 916 and thus extends beyond axial guide 916. Instill other embodiments, axial guide 916 is not included in advancementguide assembly 910. In one embodiment, the axial guide projects fromexpander 906 to be received by advancement guide assembly 910.

Advancement mechanism 932 can be used to advance medical device 110 overadvancement guide 908 and wire array 902 of advancement guide assembly910 and onto expander 906. As such, advancement mechanism 932 can besubstantially tubular, with an inner diameter slightly greater than thediameter of advancement guide 908 and wire array 902 such thatadvancement mechanism 932 can snugly fit onto and slide alongadvancement guide assembly 910. The inner diameter of advancementmechanism 932 is also less than the outer diameter of medical device 110such that a distal end face 934 of advancement mechanism 932 can contactproximal end 112 of medical device 110 to advance medical device 110distally.

As shown in FIG. 9, expander 906 is similar to expander 130, except thatproximal end 200A of expander 130 is omitted from expander 906. That is,expander 930 includes only transition portion 200C and distal end 200B.As such, a proximal end face 926 is positioned at the proximal end oftransition portion 200C. Proximal end face 926 is substantially similarin structure and size to proximal end face 204 discussed above and alsoincludes the opening to guide opening 320 that extends into expander906. Because expander 906 includes transition portion 200C and distalend 200B, expander 906 also includes wire guides 210 formed thereon.Wire guides 210 terminate at proximal end face 926.

FIGS. 11A-11B illustrate one embodiment of a method of uniformlyexpanding (and heat setting, if desired) medical device 110 usingadvancement guide assembly 910. Similar to the method illustrated inFIGS. 8A-8C, a thermal chamber 1000 is used that has an axial lengththat is substantially the same as or slightly longer or shorter thanexpander 906, as shown in FIG. 11B, and remains axially aligned withexpander 906 during the expansion process. However, because expander 906is missing proximal end 200A, thermal chamber 1000 can be substantiallyaxially shorter than thermal chamber 800.

Thermal chamber 1000 can be longer or shorter, if desired. For example,thermal chamber 1000 can extend proximally beyond expander 906 (as shownby dashed lines 1000′ in FIG. 11A) to allow medical device 110 to bepre-heated before being advanced onto expander 906.

The process can begin by positioning medical device 110 over wire array902 and advancing advancement guide assembly 910 distally towardexpander 906 so that axial guide 916 aligns with guide opening 320 inend face 926 of transition portion 200C, as shown in FIG. 11A. Toposition medical device 110 over wire array 902, advancement mechanism932 can be used. Medical device 110 and advancement mechanism 932 arefirst positioned onto the proximal end of advancement guide 908. Then,advancement mechanism 932 is advanced distally along advancement guide908, causing distal end face 934 to contact proximal end 112 of medicaldevice 110 and thereby push medical device 110 distally alongadvancement guide 908 and onto wires 904 of wiring guide 902. Medicaldevice 110 can be positioned on advancement guide assembly 910 before orafter axial guide 916 has been aligned with guide opening 320. If axialguide 916 is not used or is shorter than wiring guide 902, advancementguide assembly 910 can be positioned by aligning wires 904 with wireguides 210 on expander 906.

If desired, axial guide 916 and guide opening 320 can be configured torequire rotational alignment therebetween prior to insertion of axialguide 916 so as to better align wires 904 with wire guides 210. In oneembodiment, axial guide 916 and guide opening 320 can both have matchingnon-circular cross sectional shapes. For example, axial guide 916 andguide opening 320 can each have an oval cross section, a polygonal crosssection, or some other regular or irregular geometric cross section.

In another embodiment, shown in FIG. 12A, a key, such as radialprotrusion 928 can be formed on distal end 914 of axial guide 916 and amating key, such as notch 930, can be formed on guide opening 320 ofexpander 906 so that advancement guide 908 can only be inserted intoguide opening 320 when the mating keys are rotationally aligned.

By requiring rotational alignment before axial guide 916 can be insertedinto guide opening 320, wires 904 can be caused to be aligned with wireguides 210 before wires 904 are advanced, thereby avoiding potentialwire advancement issues. It is appreciated that other devices andmethods for rotational alignment of advancement guide assembly 910 andexpander 906 can alternatively be used.

For example, an external alignment mechanism can be used to ensure thatadvancement guide assembly 910 and expander 906 are rotationallyaligned. In one embodiment, advancement guide 908 and/or expander 906can include one or more alignment engagers which are engaged bycorresponding external alignment devices to align the two devices. Eachexternal alignment device can comprise a structure that mates with thealignment engager that is used and that, when mated, can cause theadvancement guide 908 and expander 906 to be rotationally aligned andsecured with respect to each other.

For example, as shown in the cross sectional view of FIG. 12B,advancement guide 908 can have a pair of flat spots 940 on either sidethereof. A pair of clamp arms 942 can be positioned on both sides ofadvancement guide 908 so as to be aligned with flat spots 940. Eachclamp arm 942 can have a clamping surface 944 that includes a flatsection 946 corresponding to flat spot 940. As such, when each clamp arm942 is brought toward each other, as indicated by arrows 948, flatsections 946 can press against flat spots 940 to rotationally alignadvancement guide 908. Other alignment engagers can be used, such as abore, a channel, a flange, or any other engager that can be engaged bycorresponding external alignment devices.

Returning to FIG. 11A, advancement guide assembly 910 can be furtheradvanced to cause axial guide 916 to be received within guide opening320 and distal ends 924 of wires 904 to be received on wire guides 210of transition portion 200C of expander 906. Further distal advancementof advancement guide assembly 910 causes axial guide 916 to continuethrough guide opening 320 and wires 904 to slide distally along wireguides 210 until medical device 110 becomes positioned adjacent theproximal end 926 of expander 906. If thermal chamber 1000 extendsproximally beyond expander 906, such as shown in dashed lines 1000′,medical device 110 can remain positioned adjacent the proximal end 926of expander 906 for a pre-determined period of time to be pre-heated bythermal chamber 1000.

Further advancement of advancement guide assembly 910 can cause wirearray 902 and medical device 110 to be advanced distally on expander 906to uniformly expand and heat-set medical device 110 in a similar mannerto the methods discussed above. That is, further distal advancement ofadvancement guide assembly 910 causes wires 904 of wire array 902 toadvance distally along wire guides 210 in transition portion 200C anddistal end 200B. This causes medical device 110 to also be advanceddistally on expansion member/expander 902, and to expand as medicaldevice 110 passes over transition portion 200C to the final expandedconfiguration when positioned on distal end 200B, as shown in FIG. 11B.

By integrating the wire array, axial guide, and advancement guide into asingle advancement guide assembly, several advantages can be realized.For example, because the wire array, axial guide, and advancement guideare all rigidly attached, there is no possibility of the wires of thewire array binding within the wire guides or otherwise not advancingwhen the advancement guide is advanced. Furthermore, because the wiresare rigidly attached to the advancement guide, the advancement guideassembly can be configured so that the wires will better align with thewire guides on the expansion member/expander when in use. For example,as discussed above, mating keys can be formed on the axial guide and theguide opening of the expansion member/expander to force the wires to beaxially aligned with the wire guides before the wires can be advanced.Other advantages may also be realized.

In the methods discussed above, medical device 110 and wire arrays 120and 902 are described as moving distally to engage expansionmember/expanders 130 and 906 and to expand medical device 110. However,it is appreciated that this movement is relative. As such, the axialmovement can be accomplished by any of the following: i) the medicaldevice and wire array can move distally while the expansionmember/expander remains axially stationary, ii) the expansionmember/expander can move proximally while the medical device and wirearray remain axially stationary, or iii) the expansion member/expander,the medical device, and wire array can all move axially, the medicaldevice and wire array moving in the opposite axial direction as theexpansion member/expander.

In one embodiment, medical device 110 can include a material made fromany of a variety of known suitable materials, such as a shape-memorymaterial (“SMM”) or superelastic material. For example, the SMM can beshaped in a manner that allows for restriction to induce a substantiallytubular, linear orientation while within a delivery shaft (e.g.,delivery catheter or encircling an expandable member), but canautomatically retain the memory shape of the medical device onceextended from the delivery shaft. SMMs have a shape-memory effect inwhich they can be made to remember a particular shape. Once a shape hasbeen remembered, the SMM may be bent out of shape or deformed and thenreturned to its original shape by unloading from strain or heating. SMMscan be shape-memory alloys (“SMA”) or superelastic metals comprised ofmetal alloys, or shape-memory plastics (“SMP”) comprised of polymers.

An SMA can have any non-characteristic initial shape that can then beconfigured into a memory shape by heating the SMA and conforming the SMAinto the desired memory shape. After the SMA is cooled, the desiredmemory shape can be retained. This allows the SMA to be bent,straightened, compacted, and placed into various contortions by theapplication of requisite forces; however, after the forces are released,the SMA can be capable of returning to the memory shape. Examples ofSMAs that can be used include, but are not limited to:copper-zinc-aluminum; copper-aluminum-nickel; nickel-titanium (“NiTi”)alloys known as nitinol; and cobalt-chromium-nickel alloys orcobalt-chromium-nickel-molybdenum alloys known as elgiloy. The nitinoland elgiloy alloys can be more expensive, but have superior mechanicalcharacteristics in comparison with the copper-based SMAs. Thetemperatures at which the SMA changes its crystallographic structure arecharacteristic of the alloy, and can be tuned by varying the elementalratios.

For example, the primary material of the medical device 110 can be of aNiTi alloy that forms superelastic nitinol. Nitinol materials can betrained to remember a certain shape, straightened in a shaft, catheter,or other tube, and then released from the catheter or tube to return toits trained shape. Also, additional materials can be added to thenitinol depending on the desired characteristic.

An SMP is a shape-memory polymer or plastic that can be fashioned intomedical device 110 in accordance with the present invention. When an SMPencounters a temperature above the lowest melting point of theindividual polymers, the blend makes a transition to a rubbery state.The elastic modulus can change more than two orders of magnitude acrossthe transition temperature (“T_(tr)”). As such, an SMP can be formedinto a desired shape of medical device 110 by heating the SMP above theT_(tr), fixing the SMP into the new shape, and cooling the materialbelow T_(tr). The SMP can then be arranged into a temporary shape byforce and then resume the memory shape after heating and followingremoval of the force. Examples of SMPs that can be used include, but arenot limited to: biodegradable polymers, such asoligo(ε-caprolactone)diol, oligo(ρ-dioxanone)diol, and non-biodegradablepolymers such as, polynorborene, polyisoprene, styrene butadiene,polyurethane-based materials, vinyl acetate-polyester-based compounds,and others yet to be determined. As such, any SMP can be used inaccordance with the present invention.

FIGS. 5A-5C illustrate one embodiment of a method for deploying amedical device that has been expanded using any of the methods anddevices discussed herein. FIG. 5A illustrates medical device 110positioned within a deployment device 500 that can include an outerhousing 510 and an inner portion 520 positioned within outer housing510. Inner portion 520 can be operatively associated with an actuationassembly (not shown) to advance inner portion 520 relative to outerhousing 510. In at least one embodiment, the deployment method begins bypositioning medical device 110 within outer housing 510. Medical device110 can be positioned within outer housing 510 in any suitable manner,such as through the use of a crimping device or other device that movesmedical device 110 from the expanded state to the pre-deployed stateshown in FIG. 5A.

After medical device 110 is positioned within outer housing 510, adistal end 512 of outer housing 510 can be positioned at a deploymentsite 530, as shown in FIG. 5B. With the outer housing 510 in position atthe deployment site 530, inner portion 520 can be advanced distallyrelative to outer housing 510 to urge medical device 110 from distal end512 of outer housing 510.

In alternative embodiments, medical device 110 can be constrained by athin housing or sheath. Instead of urging the medical device from withinouter housing 510, the thin housing or sheath can be pulled from medicaldevice 110. At the same time, deployment device 500 can be withdrawn andmedical device 110 can expand as the thin housing or sheath is removed.

Deployment of medical device 110 from the housing, whether using outerhousing 510 or a thin housing, can be accomplished through one or moreof: advancing a portion of deployment device 500 (e.g., inner portion520), withdrawing a portion of deployment device 500 (e.g., outerhousing 510), and advancing a portion of medical device 100, whethersimultaneously or otherwise. One of skill in the art can appreciate thatother known deployment devices and configurations can be used to deploymedical device 110.

In at least one embodiment, when medical device 110 is urged from distalend 512 of deployment device 500, medical device 110 is no longerconstrained and can expand towards its expanded state, as illustrated inFIG. 5C. In this manner, medical device 110 can be deployed atdeployment site 530.

As previously discussed, the method for forming medical device 110 canreduce localized friction or other factors to provide uniform expansionof medical device 110. Uniform expansion of medical device 110 in turncan allow medical device 110 to be deployed in the intended manner.

While various configurations have been described that include expandersthat are self expanding, it will be appreciated that expanders can alsobe used that require separate expansion mechanisms to become expanded.

For example, FIG. 6A illustrates an expansion system 600 for expandingmedical device 110 that includes an expansion mechanism 610 and anexpander 620 positionable upon expansion mechanism 610. The expander 620can be configured to receive and support a wire array 120′, thecooperation of wire array 120′ and expander 620 being usable to expandmedical device 110. For simplicity, a portion of expansion mechanism 610is illustrated as being received within expander 620 and a number ofwires 125′ of wire array 120′ have been omitted in FIG. 6A.

Expansion mechanism 610, illustrated in FIG. 6A, generally includes abody 612 having a proximal end 616 and a distal end 618. Body 612 canhave a first diameter D_(A) at proximal end 616 that transitions to asecond diameter D_(B) that is greater than first diameter D_(A). In atleast one embodiment, the second diameter D_(B) is at distal end 618,though it will be appreciated that the first diameter D_(A) cantransition to any number of varying diameters at any number of locationsbetween proximal end 616 and distal end 618.

In the illustrated embodiment, body 612 transitions from the firstdiameter D_(A) to the second diameter D_(B) at a transition portion612C. Transition portion 612C can include a tapered or ramped profilewith a shoulder portion 614A associated with proximal end 616 and ashoulder portion 614B associated with distal end 618. It will beappreciated that transition portion 612C and shoulder portions 614A,614B can have any profile and that any number of transition portions canbe provided. Expansion mechanism 610, expander 620, and medical device110 will be described with common central axis C.

Expander 620 can include a number of segmented portions 622, illustratedin FIG. 6B, separated by slots 624. Segmented portions 622 areconfigured to interface with the inside diameter of medical device 110,illustrated in phantom in FIG. 6A. In at least one embodiment, segmentedportions 622 have wire guides 210′ defined therein that are configuredto at least receive a wire array 120′. Segmented portions 622 areconfigured to interface with the expansion mechanism 610 and tooutwardly move as the diameters of the expansion mechanism 610 increase.Wire guides 210′ are defined in segmented portions 622 and are alignedgenerally parallel to central axis C.

As previously discussed, segmented portions 622 can be supported byexpansion mechanism 610. In particular, FIG. 6B illustrates segmentedportions 622 positioned over proximal end 616 of expansion mechanism610. In this position, segmented portions 622 are separated byapproximately the distance D_(A). Expansion mechanism 610 can beadvanced axially relative to expander 620 to move first transitionportion 612C and then distal end 618 into engagement with expander 620.This is similar to the axial motion of body 200 relative to medicaldevice 110 in FIGS. 4A-4C.

As expander 620 moves into engagement with transition portion 612C anddistal end 618, segmented portions 622 and wires 125′ move radiallyoutward, in the direction of the arrows illustrated in FIG. 6B,resulting in a separation of approximately D_(B), as illustrated inphantom in FIG. 6B. The radially outward movement of segment portions622 and wires 125′ uniformly expands medical device 110 in a similarmanner as described above. The expanded medical device 110 can then bedeployed by positioning the medical device in a deployment device asdescribed above.

Generally, expander 620 and/or the expansion mechanism 610 can befabricated from a variety of different materials. By way of example,expander 620 and/or expansion mechanism 610 can be made from metals,alloys, plastics, polymers, composites, ceramics, quartz, glass,combinations thereof, or other materials, as desired, based upon theparticular medical device being formed and the temperatures and/orpressures that expander 620 and/or expansion mechanism 610 are towithstand during the manufacture of the medical device.

In one embodiment, expander 620 and/or expansion mechanism 610 can befabricated from stainless steel or nitinol. In another embodiment, thematerials can withstand a temperature from about 250° C. to about 600°C., from about 250° C. to about 650° C., from about 300° C. to about600° C., from about 300° C. to about 550° C., from about 450° C. toabout 600° C., or some other range known to one skilled in the art inview of the teaching contained herein.

FIGS. 7A-7B illustrate another embodiment of an expander 700. Expander700 can include a rolled configuration in which expander 700 includes afirst end 704, a second end 706 and a central portion 708. Wire guides210″ can be formed in expander 700 between first end 704 and second end706 and can receive wires 125″. In such a configuration, first end 704and second end 706 are separated by at least one angular separation andcentral portion 708 is curved to define a central lumen 702. In such aconfiguration angular separation between first end 704 and second end706 can be increased. In particular, overlap between first end 704 andsecond end 706 can be described as negative angular separation while agap between first end 704 and second end 706 can be described aspositive angular separation.

Accordingly, a negative angular separation A_(A) is shown in FIG. 7A inwhich first end 704 and second end 706 overlap. The angular separationA_(A) shown in FIG. 7A can be established when expander 700 is inengagement with a proximal end of an expansion mechanism, such asexpansion mechanism 610 described above, upon insertion of expansionmechanism 610 within central lumen 702. Axial movement of expansionmechanism 610 can expand expander 700 to change the angular separationbetween first end 704 and second end 706 to a positive angularseparation A_(B) shown in FIG. 7B. A wire array 120″, similar to theother wire arrays described herein, can be positioned in wire guides210″ such that as expander 700 is expanded, wire array 120″ and expander700 are also expanded to allow expansion of a medical device asdescribed above.

Generally, expander 700 can be fabricated from a variety of differentmaterials. By way of example, expander 700 can be made from metals,alloys, plastics, polymers, composites, combinations thereof, or othermaterials, as desired, based upon the particular medical device beingformed and the temperatures and/or pressures that expander 700 is towithstand during medical device manufacture. In one embodiment, expander700 can be fabricated from stainless steel or nitinol. In oneembodiment, the materials can withstand a temperature from about 300° C.to about 600° C.

While one type of expansion mechanism has been provided for expandingexpanders 620 and 700, it will be appreciated that other types ofexpansion mechanisms can be used in a process in which a medical deviceis expanded with a wire array.

As noted above, although the embodiments discussed herein employ wiresas the transport mechanisms, it is appreciated that other types oftransport mechanisms can alternatively be used according to the presentinvention. For example, strips, ribbons, yarns, threads, rods, or otherstructures can be used as the transport mechanisms, as long as thosestructures have the desired strength and rigidity, with associatedflexibility and resiliency to allow the structure to i) provide abearing-type surface for the medical device, ii) separate at least aportion of the medical device from an expander or expander mechanismduring a manufacturing process, or iii) otherwise perform otherfunctions described or identified from the description contained herein.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. For example,slight modifications of the mandrel are contemplated and possible andstill be within the spirit of the present invention and the scope of theclaims. The scope of the invention is, therefore, indicated by theappended claims rather than by the foregoing description.

What is claimed is:
 1. A system for uniformly expanding and heat settinga medical device, the system comprising: a thermal chamber; and anexpander at least partially positioned within the thermal chamber, thethermal chamber maintaining the expander at a predetermined elevatedtemperature, the expander being configured to: uniformly expand amedical device as the medical device is advanced over the heatedexpander; and heat set the expanded medical device while the medicaldevice is positioned on the heated expander.
 2. The system of claim 1,wherein the expander extends longitudinally between a proximal end and adistal end, the expander having an outer surface with a plurality oftransport guides formed thereon that extend longitudinally from theproximal end toward the distal end; and the system further comprises: atransport assembly extending between a proximal end and a distal end,the transport assembly comprising a plurality of transport mechanismseach extending longitudinally between the proximal and distal ends ofthe transport assembly, the distal ends of the transport mechanismsbeing receivable within and slidable along the transport guides, thetransport assembly being configured to receive a medical device thereonand position the medical device radially over the expander, and theexpander being configured to radially expand the medical device whilethe medical device remains on the transport assembly.
 3. The system ofclaim 2, further comprising an axial guide that longitudinally guidesthe transport assembly when the transport mechanisms of the transportassembly are received within and slide longitudinally along thetransport guides.
 4. The system of claim 3, wherein the expander has aguide opening extending distally thereinto from a proximal end face, andthe axial guide is receivable within the guide opening to longitudinallyguide the transport mechanisms of the transport assembly to the wireguides and to guide the transport mechanisms as the transport mechanismsslide longitudinally along the transport guides.
 5. The system of claim3, further comprising means for rotationally aligning the axial guideand the expander.
 6. The system of claim 5, wherein the means forrotationally aligning the axial guide and the expander comprises: theaxial guide and the expander having mating shapes; or mating keys formedon the axial guide and the expander.
 7. The system of claim 2, whereinthe expander has a tapered portion positioned between the proximal anddistal portions, the tapered portion having a cross sectional area thattransitions between the cross sectional area of the proximal portion andthe cross sectional area of the distal portion.
 8. The system of claim2, wherein the transport guides are circumferentially distributed aboutthe outer surface of the expander.
 9. The system of claim 2, wherein thetransport mechanisms and the transport guides are configured so that themedical device is physically separated from the expander when themedical device is positioned radially over the expander and expanded bythe expander.
 10. The system of claim 2, wherein the plurality oftransport mechanisms comprises a plurality of wires, the transportassembly comprises an array of the wires, and the plurality of transportguides comprises a plurality of wire guides.
 11. A method ofmanufacturing a medical device, the method comprising: forming a medicaldevice from a tube having a first diameter; uniformly expanding themedical device from the first diameter to a second diameter at which themedical device can be left within a body vessel, the medical devicebeing expanded from the first diameter to the second diameter whilebeing continuously positioned on an expander; and heat setting theexpanded medical device at the second diameter while the medical deviceis positioned on the expander.
 12. The method of claim 11, wherein heatsetting the expanded medical device comprises maintaining the expandedmedical device at the second diameter on the expander for apredetermined period of time while the expander is maintained at apredetermined heat-setting temperature.
 13. The method of claim 12,wherein the expander is positioned within a thermal chamber thatmaintains the expander at the predetermined heat-setting temperatureduring the steps of uniformly expanding the medical device and heatsetting the expanded medical device.
 14. The method of claim 11, whereinthe medical device is comprised of a shape-memory material.
 15. Themethod of claim 11, wherein the medical device is physically separatedfrom the expander when the medical device is positioned on the expander.16. The method of claim 11, further comprising: preheating the medicaldevice within a thermal chamber before uniformly expanding the medicaldevice; and maintaining heat on the medical device within the thermalchamber during radial expansion of the medical device.
 17. A method ofmanufacturing a medical device, the method comprising: positioning amedical device on a transport assembly having a plurality of transportmechanisms, the transport mechanisms being arranged generally parallelto a central longitudinal axis; positioning a portion of the transportassembly on an expander so that the medical device becomes positionedradially over the expander; radially expanding the medical device withthe expander while the medical device is positioned on the transportassembly; and heat setting the expanded medical device while the medicaldevice is positioned on the expander, the acts of radially expanding themedical device and heat setting the expanded medical device beingperformed while the medical device is positioned in a heated thermalchamber.
 18. The method of claim 17, wherein positioning the portion ofthe transport assembly on the expander comprises: positioning ends ofthe transport mechanisms of the transport assembly in transport guidesformed on the expander; and moving the transport assembly longitudinallywith respect to the expander so that the transport mechanisms slidealong the transport guides until the medical device is positionedradially over the expander.
 19. The method of claim 18, whereinpositioning the portion of the transport assembly on the expanderfurther comprises: inserting an axial guide into a guide openingextending longitudinally through the expander, the transport assemblybeing attached to the axial guide so as to move therewith, and whereinthe steps of positioning the ends of the transport mechanisms in thetransport guides and moving the transport assembly longitudinally areaccomplished by moving the axial guide along the guide opening.
 20. Themethod of claim 17, wherein radially expanding the medical device withthe expander comprises moving the medical device relative to theexpander from a first position on a first portion of the expander to asecond position on a second portion of the expander, the first andsecond portions of the expander respectively having first and secondcross sectional areas, the second cross sectional area being greaterthan the first cross sectional area, the medical device being radiallyexpanded as the medical device moves from the first position to thesecond position.